Plastics are becoming increasingly useful substitutes for heavier materials in industry and manufacturing. In industries where weight, or weight reduction is critical, plastics can offer solutions to certain desired results in terms of improving a product's overall performance. When a substrate material must be transparent, such as, for example windows or windshields, glass windows and windshields, though heavier and more expensive, remain the benchmark material in terms of transmissivity and strength. Nevertheless, there is a movement to substitute polymeric materials, such as acrylic or polycarbonate materials, etc. for glass materials to reduce weight and assist objects such as vehicles to meet various fuel consumption and other performance standards, etc.
Many polymeric materials, such as, for example acrylic materials, can be made to be adequately transparent. However such materials are softer than glass and can be susceptible to scratches, abrasions and erosion through use, especially when used in high speed environments. Such surface abrasions can lead to crazing when operational stresses are applied to components such as windows and windshields used in vehicles including, for example, aircraft.
Coatings deposited onto various transparent polymeric component substrates are often desirable for expanding the usefulness of substrates having certain desirable physical or chemical characteristics (e.g. low cost, transparency, etc.); especially if the component substrates do not possess adequate strength, durability, scratch resistance, hardness, etc. Applying a coating to such substrates, therefore, may allow one to achieve desired characteristics, especially surface characteristics of transparent components.
Plasma deposition systems able to deliver very thin film coatings to substrate surfaces are known. Vacuum deposition refers to a family of related procedures used to deposit layers of material on an atom-by-atom or molecule-by-molecule basis onto a substrate surface. Such procedures, as their name suggests, operate at pressures well below atmospheric pressure (i.e. under vacuum). The deposited layers or thin film coatings can be deposited at thicknesses of from one atom up to millimeters. Since such processes must be conducted under vacuum, the vacuum chamber must be large enough to contain components being coated. Therefore, plasma deposition is practically restricted to components that are small enough to be placed within a vacuum chamber or low pressure environment. Put another way, the limiting factor in a vacuum plasma deposition process is often the size of vacuum chamber.
Atmospheric plasma deposition refers to a plasma deposition process that is conducted at ambient pressure. Therefore, such atmospheric plasma deposition processes do not require a vacuum chamber within which to deposit a coating onto a substrate. Since no vacuum is required or involved, such atmospheric plasma deposition processes can offer greater processing flexibility for coating processes.
Atmospheric plasma deposition processes for depositing differing, thin coatings onto substrates are known, whereby multiple layers of various and differing coatings are deposited onto a substrate to impart various characteristics onto a substrate
Siloxane-containing thin film coatings are known in the manufacture of substrates, including transparent materials used for windshields and windows. Transparent polymeric substrate materials are desirable over glass for use in vehicular windshields and windows in terms of weight, cost, safety, etc. However, since non-glass transparent materials often suffer in terms of erosion, abrasion, etc., this lack of material durability impacts repair and replacement schedules, as vehicles must be taken out of service to repair and replace.
Various coating layers have been attempted to provide adequate strength and characteristics to substrates, including transparent substrates. However, the complexity of delivering numerous coating layers or varying thicknesses, with each coating having desired characteristics to improve or preserve the characteristics and usefulness of substrate materials has led to uneven and costly performance in the field.